In particular, the present invention relates to an extrusion device of the type comprising an extrusion head, in turn comprising a number of shaped plates, a wire or ply reinforcement guiding device and a die, and releasable clamping means for packing the plates together. When packed together, said plates define an intermediate guide duct for reinforcing wires and two supply ducts for extruded elastomeric material located on opposite sides of the guide duct, and provide for locking together the wire guiding device and the die.
In known extrusion devices of the aforementioned type, said clamping means normally comprise a number of rods fitted through said plates and having threaded end portions engaged by lock nuts which, once the plates have been packed together on a press, provide for locking them in the packed position. Said rods are usually fitted along the edges of the plates, but cannot be equally spaced to prevent interfering with the supply and guide ducts. This therefore results in uneven clamping pressure and possible distortion of the plates, in turn resulting in poor sealing and leakage of elastomeric material from the lateral surfaces of the extrusion head.